1. FIELD OF THE INVENTION
The present invention relates to an electronically controlled fuel injection system in which computational operations are performed by employing as principal engine operating parameters the amount of air drawn into an internal combustion engine and the number of revolutions of the engine, and the proper fuel injection quantity is computed in the form of a digital quantity to inject fuel into the engine.
2. DESCRIPTION OF THE PRIOR ART
Electronically controlled fuel injection systems are known in the art in which electronic elements such as capacitors, resistors, transistors, etc. are employed, and the required fuel injection quantity is analogically computed in accordance with the values representing the amount of air drawn into the engine and the number of revolutions of the engine as principal engine parameters and the values representing the engine cooling water temperature, wide-open throttle, idling condition, engine start, voltage variation, etc. constituting auxiliary engine parameters to thereby inject the proper amount of fuel into the engine. A disadvantage of the conventional system of such analog type is that the effects of the deterioration of the electronic elements with temperature and time are so great that the operation of the system is rendered unstable. Another disadvantage of this type of conventional system is that the adjustment is required at a number of places because of the variations in the performance of the electronic elements of the similar type or kind, and moreover the occurrence of electrical noise due to the high tension discharge in the ignition circuit or the like causes the system to operate unstably.